Electric heating system



I 1,626,221 P" 26 1927' s. R. BLAKESLEY ELECTRIC HEATING SYSTEM.

Filed Dec. 7. 1922 2 Sheets-Sheet 1 "lllllliml;

illulllmmnmmm wlqm J W l ,62 6,221 P" 26 1927' q. R. BLAKESLEY ELECTRIC HEATING SYSTEM Filed Dec. '7. 1922 2 Sheets-Sheet 2 asses Jqvaghsg Patented Apr. 26, 192 7. UNITED STATES I PATENT OFFICE. I aroma a. I I 1 a ,"or wisconsrn.

Application filed December 7, 1988. Serial No. 005,855.

This invention relates to a three heat threewire electric switch for the control of heating elements in electric heating and cooking appliances wherein a plurality of degrees of heating effect is desirable. This invention has special reference to three wire circuits comprising one or two generators or transformers in series with two main leads and a neutral. In such a system the voltage across the main leads will be twice that between either main lead and the neutral.

As ordinarily installed a group of heating or cooking appliances may be installed on one side of a transformer in such a way as to cause an unbalanced load that results in an unusually large pressure drop. For example, cases have been found where most of the ovens in a group of ranges have been installed on. one side of the transformer and the top plates on the other side with the result that the load may fall on one side at the usual baking time and on the other side at meal times, aggravating the unbalanced transformer load and the resulting large voltage drop which slows up the heating time of the entire group of ranges. For example, instances have been found where the addition of one hot plate caused a drop of 5 or 6 volts on a normal 110 volt circuit. Two such plates would cause an increased drop resulting in both units operating far below their rated voltage.

It is an object of this invention to cause a uniform distribution of load over the lines when any or all units are turned on full. thus eliminating the need of an analysis of each group of ranges or thelike in an attempt to distribute the load. a

It is another object of this invention to devise a three wire. three heat switch that by means of a control of the voltage secures the desired varying degrees of heat without using a rheostat.

It is an important object of this invention to devise a switch which will, for example,

connect two 110 volt heating units in series across a 220 volt line for high heat, thus halving the amperage and doubling the voltage resulting in only one quarter the voltage drop as comparedto a 110 volt line and more nearly maintaining the standard voltage as a more heating units are added to the line. It will be apparent that the same relative advantages apply to voltages other than the 220 and 110 mentioned.

It is another important object of this inelements across a line carryin vention to connect one of the two heatin voltage of the element to provi e a medium heat half'that of the high heat, thereby utilizing the one element at its most efficient voltage.

It is still another important object of this I invention connect the two previously men tioned heating elements in series across 110 volts for low heat, resulting in the use of the rate half the rated voltage on each element and illustrated in the drawings and hereinafter more fully described.

On the drawings: 7 Figure 1 is a top plan view of a switch fembodying a preferred form of this inven- Figure 2 is a partial section on the line 2-2 of Figural.

Figure 3 is a section on the line 3-3 of Figure 2. i

Figure 4 is a partial section on the line 4-4 of Figure 3.

F1gure 5 is a diagrammatic layout of the clrcuits for high heat.

Figure 6 is a diagrammatic layout of the circuits for medium heat.

Figure 7 is a diagrammatic layout of the circuits for low heat. I

As shown on the drawings:

The numeral 1 refers to a switch cover harmg suitable indicia 2 thereon such as .Ofi', Low, Medium and High, or Off, 1, 2 and 3. The cover may be removable if desired, as when wires are to be attached within an insulated body 3. Normally, however, it is intended to attach all wirlng at the base of the switch. Suitableswitch contacts are provided at a! plurality of levels, as will be hereinafter described in detail, and movable contacts are mounted on a pivot 4 at corresponding elevations and adapted to be moved as a unit by any well-known snap mechanism (not shown) in connection with a knob or switch handle 5.

' The switch contacts in the preferred embodiment of this inventionare disposed in 7, three levels or stages, A, B and C, each having one contact connected respectively to a main line wire 6, a: neutral wire 7 and the second main line 8,-of a three wire system from one or two transformer sides or generators operating in series. In such an arrangement of wirlng the voltage across the two main line wires 6 and 8 will be twice the voltage across either mainline and the neutral line. As a specific example in the following take 220 volts across the mam lines.

The particular arrangement of the three contact stages is immaterial 'but for simplicity we will consider A asthe top stage having a connection 9 to main line wire 6 leading to an ofiset contact 10 which is shorter than any of the other stationary contacts so that when the corresponding movble contact 11 is in off position the short arm 12 thereof will not make contact. A second stationary contact 13 for stage A is connected by a wire 14 to one terminal of a 110 volt element 15, the other end of which is connected to a: similar element 16 which is in turn connected to contacts 17 and 18 of stages B and C, respectively, by means of a common binding post'19, as shown in Fig. 2.

The neutral line wire 7 is connected to a contact 20 in stage B, and a third contact. 21 in this stage is connected by a wire 22 to the junction between the heating elements 15 and 16. The main line wire 8 is connected to a contact 23 in stage C. A movable contact 24 operates in the plane of stage B and a similar contact 25 operates in the plane of stage C. In the wiring diagrams of Figs. 5, 6 and 7 the complete wiring is shown in each case and the particular circuit in use for high, medium, and low heats in Figs. 5, 6 and 7 respectively, are indicated by relatively heavy lines.

In Fig. 5 the circuit leads from the main wire 6 through the contact 10 of stage A and movable contact 11 to contact 13, thence through wire 14 to the heating elements 15 and 16 in series, thence to contact 18'of stage C through the movable contact 25 to contact 23 which is connected to the line wire 8. It will then be evident that 220 volts is carried through two 110 volt heating elements in series togive the high heating connection.

For medium heat a 90 clockwise turna's shown in Fig. 6 embraces the samecircnit from the main line connection 6 through contacts 10, 11 and 13 to the heating element 15. In this case the neutral wire 7 makes contact through 20, 24, 21 and 22 of stage line 7 servesto energize one element 15 to its full capacity.

For low heat a further 90 turn leaves' the main line connection through stage A as before and switches the stage B connection to contact 17 and thence to the terminal of the heatlng element 16, resulting in placing the two heating elements 15 and 16.-across 110 volts or half the rated voltage for each element. It will be noted that the short arm 12 of the movable contact 11 of stage A makes contact with the contact 13, which is of normal length, but fails to make contact with contact 10 which is purposely shorter to prevent contact therewith when the switch 1s m ,0 position, as shown in Figs. 2 an 3. It will be apparent that in off position all three line wire stationary contacts in the different stages are broken so that an accldental ground anywhere beyond these contacts does not result in a short circuit, nor do any of the wiring or heating elements carry potential danger as being a live wire 4 when the switch is in off position.

From the above description it will be evident that I have produced a comparatively simple three heat three wire switch that will be trouble-proof in use because of the extreme simplicity of the required wiring.

I am aware that numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patcnt granted otherwise than necessitated by the prior art.

I claim as my invention:

1. In combination, a two part heating unit, a three wire supply system comprising two main lines and a neutral line, and means comprising an electrical switch for selectively connecting the two parts of said unit n series across the main line voltage, or connecting one part of said unit across one main line and the neutral line or for connecting the two parts in series across one main line and the neutral line.

2. In a three wire heating system comprising two main lines and a neutral line, a two part heating unit, in combination with aswitch for selectively connecting the two parts of said units in series across the main lines or connecting one part of said unit across one main line and the neutral line.

3. In a three wire heating system comprising two main lines and a neutral line, a two part heating unit and means comprising an electrical switch for connecting the parts of said unit in series across the main lines or comprising two main lines and a neutral line, and means comprising a switch for selectively connecting one part of said unit across one main line and the neutral line, or connecting both parts of said unit across one main line and the neutral line.

A three heat system comprising a two part heating unit and a three wire supply system therefor, and means for selectively connecting said unit and supply system for producing high, medium or low heat.

6. In combination, a plural section heating coil, and means to connect one-of said sections from one side of an Edison three wire system to the'neutral thereof or both sections in series from one side of said system to the other side thereof independently of said neutral.

7. In combination, a plural section heating coil, and means to connect one of said sections from one side of an Edison three wire system to the neutral thereof or both sections in series from one side of said system to the other side thereof.

8. In combination, aplural section heat ing coil, and means to connect the two sec-- tions thereof in series between one side of an Edison three wire system and the neutral thereof or between one side of said system and the other side thereof independently of said neutral.

9. In combination, aplural section heating coil,and means to connect-the two sections thereof in series between one side of an Edison three wire system and the neutral thereof or between one side of said system and the other 'side thereof.

10. In combination, a plural section heating coil, and means to connect the two sections thereof in series between one side of an Edison three wire system and the neutral thereof or one of said sections between said side of said system and the neut :11 thereof or the two sections thereof in series between said side of said system and the other side thereof independently of said neutral.

11. In combination, a plural section heat ing coil, and means to connect the two sections thereof in series between one side of an Edison three wire. system and the neutral thereof or one of said sections between said side of said system and the neutral thereof or the two sections thereof in series between said side of said system and the other side thereof. v,

12. In combination, a plural section heatin, coil, and means to connect the two sections thereof in series between one side of an Edison three wire system and the neutral thereof or one of said sections between one side of said system and the neutral thereof or the two sections thereof in series between said side of said system and the other side thereof independently of said neutral.

13. In combination, a plural section heating coil, and means to connect the two sections thereof in series between one side of an Edison three wire system and the neutral thereof or one of said sections between one side of said systemand the neutral thereof or the two sections thereof in series between said side of said system and the other side thereof.

In testimony whereof I have hereunto subscribed my name.

GEORGE R. BLAKESLEY. 

